Barrel plating apparatus and process



Feb. 28, 1933. I c K ET AL 1,899,679

BARREL PLATING APPARATUS AND PROCESS Filed June 5, 1926 2 Sheets-Sheet l cou c. FINK RALPH D SH 6 their a Zfarn.

Feb. 28, 1933. c. G. FINK ET AL 1,899,679 S BARREL PLATING APPARATUS AND PROCESS Filed June 3, 1926 2 Sheets-Sheet 2 RALPH D. EASH by the raifE r/zey Patented Feb. 28, 1933 UNlTED STATES PATENT OFFICE COLIN G. FINK, 10F NEW YORK, N. Y., AND RALPH D. EASH, OF EAST ORANGE, NEW

JERSEY, ASSIGNORS TO CHEMICAL TREATMENT COMPANY, INC., OF

CORPORATION OF N EW YORK NEW YORK, A

BARREL PLATING APPARATUS AIiTD PROCESS I Application filed June 3, 1926. Serial No. 113,390.

. drawings, wherein Figure 1 is ment. g

Fig. 2 is a vertical sectional View on the line 22, Fig.1.

Fig. 3 is a cross-section on the line 33, Fig. 2.

Fig. 4 is a longitudinal sectional new of the anode.

Fig. 5 is a view similar to Fig. 2 ofthe second. embodiment. I 1

Fig. 6 is a crosssectional view on the line 6-6, Fig. 5.

Referring to said drawings, numeral 10 designates a barrel, mounted to turn, as by being provided with trunnions 12, 13 Journalled in suitable bearings 15. The barrel may be rotated through a gear 18 or other suitable means. The barrel 10 is made conducting so as to have electrical connectlon with the articles placed therein, which articles are to have the plating metal deposited thereon and hence are the cathode. The current transmitted to the barrel conveniently flows off through the trunnions 12, 13 and leads 20 to the feeder 22 connected to the nega top plan view of one embodiative side of the current source, the connec-. tion between the trunnions 12 and 13 bemg conveniently through a sliding connection, as for example rings 24 and brushes, mercurycups, or the like, mercury-cups 26 being here shown. Both trunnions 12 and 13 are preferably used to carry the current in View of the heavy currents usually employed.

The barrel 10 is preferably made of metal and a metal is preferably chosen which is a poor recipient of the metal which is to be deposited from the bath. In chromium baths, iron is preferably used.

1y comprise means for continuously rotating the barrel (comprising the gear 18) and flat sides 30 on the barrel, the barrel being conveniently hexagonal, as shown.

Any suitable means, as a door 31, may be provided for putting articles in and removing them from the barrel.

An anode 33 is placed inside of the barrel 10,'and preferably runs the length thereof. In the embodiment illustrated in Figs. 1-4, the anode 33 is conveniently supported on a shaft 35 which runs through the trunnions 12, 13 (made hollow for the purpose) and is insulated therefrom, as'by means of the in- 'sulating sleeves 37. The shaft 35 and sleeves 37 fit snugly in the hollow trunnions 12 and 13 and turn therewith. Current flows to the anode 33 from feeder 40, leads 42, 42 and the shaft 35, sliding connections 44, 44 similar to 24, 26 being conveniently provided between the 'two endsof the shaft 35;and the leads 42, 42.

In the embodiment shown in Figs. 5 and 6, the anode 33 may be made stationary. In this embodiment the anode may be supported on a shaft or beam supported at'its ends in brackets or the like 7 2, 73 at the sides of the tank. The barrel 10 is supported by hollow shafts or sleeves 12', 13', which are preferably made of an inside diameter larger than that of the shaft 70, whereby to leave a considerable clearance or space 75 between the shaft 70 and sleeves 12', 13' forinsulation purposes. The barrel 10 is rotated (as in the first embodiment) by a gear 18 on one (or both) of the sleeves 12', 13. 1

The ends or heads 50, 51 of the barrel, as illustrated in both embodiments, may be insulated or shielded from the anode (where,

as is preferably the case, the ends of the allode closely approach theends of the barrel) as by means of disks 53, 54 of glass or other suitable insulating material.

Also where the ends of the anode 33 approach the ends of the barrel 10, the ends (30, 61 are preferably made hollow or recessed so as to be spaced from the barrel ends or heads opposite said anode ends 60, 61. By thus spacing the ends, the conducting path from an exposed part of the anode to the ends or heads of the barrel is made comparatively long, so as to cut down current leakage through such film or electrolyte as may extend from the anode to the said barrel ends (which conduct cathode current).

Means 80 may also be provided for insu lating or shielding the barrel 10 between the ends to prevent loss of current, etc. Such means is shown in Figs. 5 and 6. Similar means may be provided in the embodiment shown in Figs. l4. This means 80 comprises insulation interposed between the anode and those parts of the barrel dipping into the bath and not covered by the cathode work. The insulation is conveniently a pair of plates 82, 83 of porcelain, for example, hanging down on each side of the anode, and separated approximately the width of the pile of work resting on the barrel surface. The plates 82, 83 are conveniently hinged to a support 85, so as to ad]ust themselves to piles of Work of different width. The support 85 is preferably made separate from the anode, so as to be readily removable (together with the plates 82, 83 hinged thereon) from the barrel, so as to be readily removed, for example, in charging the barrel with work. Or, one or both of the plates 82, 83 may be made short enough to swing over onto its back side, to facilitate examination and charging of the work.

A temperature regulating means 66, as a coil through which a heating or cooling fluid may be circulated, is preferably provided for controlling the temperature of the bath. Where a tank 28 is used in connection with the barrel, the temperature-regulating means is placed therein. With a liquid-tight barrel,

the heating or' cooling medium could be brought into contact with the barrel, as by playing a stream of hot or cold water thereon, or by partially immersing the barrel.

A selective action of the current to bring about a maximum deposition on the cathode articles and a minimum or nil deposition on the barrel 10, and also a good throwing of the metal being deposited (so as to prevent burning, rough deposits, etc. of the metal on the articles nearest thevanode) is provided by regulating the distances of the cathode articles, and of the barrel surface,

from the anode. There should be a substantial difference, however, between the resistance between theanode and barrel, and the resistance between the anode and the cathodearticle mass, to inhibit deposit on the barrel surface or loss of current thereto.

Bright plate in barrel plating with chrovminim-containing solutions are more readily obtainable with chromic acid solutlons of- A hydrogen film of a de nite thickness being necessary foreflecting deposition of chromium from chromic acid solutlons, it has been found desirable to disturb the cathode.

mass infrequently, consistent with a rearrangement of the articles in the mass for distribution of the deposit over the articles, and all parts thereof in the mass, so as to maintain a uniform hydrogen film for moderate periods on the articles. For good plating conditions, the articles should not be tumbled more frequently than 15 times per minute (thereby providing a pause of about 4 seconds between tumbles), the most desirable range being between 3 and 6 tumbles (inclusive) 4 per minute, providing pause durations of 20- 10 seconds. lVith a rotating barrel of hexagonal construction, the pocket in the angle between two fiat sides reaches a certain height before the articles move, and when a certain height is reached they are thrown rather suddenly into the next pocket formed in the angle between the hexagonal sides. At onehalf revolution per minute, of the barrel, the articles therein will receive three tumbles per minute.

The apparatus invention may receive other forms of embodiment than those herein specificall y illustrated and described, and the process may be carried out in other modes of procedure than those specifically described.

What is claimed is 1. A barrel electroplating apparatus for Illi said anode and with said cathode for effect.

ing a flow of current to said electric plating apparatus.

2. A barrel electroplating apparatus for plating metals of the chromium type which require the utilization of relativel high current densities comprising a tank or holding chromium plating solution, a metallic barrel having a cyllndrical or polygonal sur-' face having bare metallic ends and a bare metallic body containing a multiplicity of perforations and rotatively mounted over said tank on hollow shafts extending laterally of the ends of the barrel, a metallic anode having a cylindrical or polygonal surface and rotatively mounted axially of said barrel on shafts extending laterally of said anode and through but insulated from the aforesaid hollow shafts and insulating means interposed between the ends of the anode and the ends of the barrel for shielding the ends of said barrel and for causing a direct flow of current from the cylindrical or polygonal surface of the anode to the bare metallic body and the articles held therein via the plating bath, said insulating means being constituted of inert material which is incapable of detrimentally affecting the plating bath or of having a reducing action thereon, and electrical connections respectively connected with said shafts and hollow shafts for conductin electric current to the anode and barrel cat$de respectively.

3. A barrel electroplating apparatus of the character set forth in claim 2 in which the anode and the barrel constituting the cathode are made of iron.

4. A barrel electroplating apparatus of the character set forth in claim 2 in which the electrical connections to the shafts include discs mounted on said shafts and dipping in mercury cups.

5. A barrel electroplating apparatus in the character set forth in claim 2 in which the metallic barrel has a hexagonal form.

6. In the method of electrodepositing chromium in a barrel plating apparatus involving the utilization of high current densities that improvement which comprises limiting the number of tumbles to approximately 15 tumbles or less drogen film on t e articles to be plated is not detrimentally affected.

7 In the method of electrodepositing chro- 5 mium in a barrel plating apparatus involving per minute whereby the hythe utilization of high current densities that surface of the barrel whereby the deposition of chromium on the bare surfaces of the barrel is practically inhibited.

8. The method of electrodepositing chromium upon articles electrically cathodic in a barrel plating apparatus, which comprises providing a pause of 4 seconds or more between successive tumbles of the objects during the passage of current to said articles. 9. The method of electrodepositing chromium upon articles electrically cathodic in a barrel plating apparatus, which comprises limiting the number of tumbles to 15 tumbles or less per minute during the passage of current to said articles.

10. The method of electrodepositing chromium from'a chromic acid plating solution upon artlcles electrically cathodic in abarrel plating apparatus, which comprises. providing between successive tumbles, during the passage of current to said articles, a pause of duration sufficient to electrodeposit chromium over the exposed part of the objects.

11. The method of electrodepositing chromium upon articles electrically cathodic in a barrel plating apparatus, which comprises limiting the number of tumbles to 15 tumbles or less per minute during the passage of current to said articles and maintaining a concentration of approximately 200-300 grams per liter of chromic acid in the plating bath.

In witness whereof, we have hereunto 

